S T R ^ A. 



Plate 

 Species 14. (Mus. Brit.) 



OsTP.,EA DENTicuLATA. Ost. testd subrotuiidd, cTassd, 

 glahrd, submargaritaced ; intus parlim fusco- 

 purpureo subiridescenti ; valindd inferiori magnd, 

 planatd, niarginibus albidis viridescentibus, late 

 foliaceis ; valvuld superiori convexd, obscure tidier- 

 culatd, aureo-fulvd Jusco rubescenle concentrice 

 strigatd; cardine planulato ; margine intemo valide 

 denticulato. 



The denticulated OsTRiEA. Shell subrotund, thk-k, 

 glabrous, a little margaritaocous ; within, in parts 

 brownish purple, rather iridescent; lower valve 

 large, flattened, with greenish-white borders, 

 widely foliaceous ; upper valve convex, obscurely 

 tuberculated, golden-brown, concentrically striped 

 with reddish-brown ; hinge flattened, internal 

 margin strongly denticidated. 



Born. Mus. tab. C, f. 910. 



Hob. America ? 



The figure of Chemnitz fairly enough represents the 



species in a very worn state ; while that copied in the 



Encyclopaedia might almost have been drawn from our 



shell. 



Species 15. (Mus Brit.) 

 OsTR.ffiA LURIDA. Ost. tesld tenidusculd, luride, glaucd, 

 sublcevigatd, prope marginem veniralem leviter 

 plicatd ; postice plerumque productd, valvuld 

 inferiori profundd, margine dorsali angusto ; 

 valvuld superiori subcequali, leviter convexd. 

 The lurid Ostr.«;a. Shell rather thin, darkly glaucous, 

 rather smooth, lightly plicated near the ventral 

 margin; mostly produced posteriorly; lower valve 

 deep, dorsal margin narrow ; upper valve nearly 

 equal in extent to the under, slightly conve.x. 



Carpenter. ? MS. Mus. Brit. 



Hab. Mazatlan. 



The chief characteristic of this species is the pecu- 

 liarly lurid glaucous tint pervading the inner and 

 outer surface of both valves. 



Species 16. (Mus. Brit.) 

 Ostr^a fyxidata. Ost, testd orbiculari, inxquivalvi, 



January 



IX. 



pallide fulva ; valvuld inferiori convexissimd 

 radiatim costatd, costis nodulosis, scepe duplicatis ; 

 valvuld superiori pland, divaricatim costatd, costis 

 nodidosis ; marginibus ventralibus crenulatis. 



The box-shaped Ostr^a. Shell orbicular, inaqui- 

 valve, pale fulvous; lower valve very convex, 

 radiately ribbed, ribs nodulose frequently dupli- 

 cate ; upper valve flat, divergently ribbed, ribs 

 nodulose ; ventral margins crenulated. 



Adams .wid Keeve. Zool. Voy. Samarang. p. 72, 

 PI. xxi. f 19. 



Hah. Philippine Islands. 



A very characteristic little species, sculptured with 

 finely beaded diverging ribs, with very deep under, and 

 flat opercular upper valve. 



Species 17. (Fig. a, Mus. Brit, b, Sowerby.) 



Osti:.i:a rhizophorje. Ost. testd elongato-subtrigond, 

 tenuiuaculd, lax issime foliaced ; sordide J'ulvd, 

 prope marginem ventralem squamatd, suhpUcatd, 

 compressd, expansd, strigis purpureis inierruptis 

 vershs apicem medio divisis pictd ; intus albidd ; 

 valvuld inferiori profundd cardine producto ; 

 valvuld superiori planulafd. 



The Mangrove Ostr^a. Shell elongated-subtrigonal, 

 rather thin, very loosely foliaceous ; dull fulvous, 

 squamose, slightly plicated, compressed, expanded 

 near the ventral margin, painted with purple 

 interrupted stripes divided in the middle towards 

 the apices ; whitish within ; lower valve deep, 

 hinge produced ; upper valve flattened. 



GuiLDiNG. Zool. Journal, vol. 3. p. 512. 



HcdL Caribbean Islands. West Indies. 



The species is not found exclusively attached to the 

 roots of mangrove, although that may possibly be 

 regarded as its normal habit. From the South African 

 species of the same general habit, 0. parasitica, it may 

 be distinguished by its less solid and less elongated 

 form. The large specimen, fig. b, represents the 

 appearance of the shell when attached by a small por- 

 tion of its surface to rocks. 

 , 1871. 



